The present invention generally relates to a facsimile apparatus which in a transmission mode codes image data scan line by scan line and transmits them as facsimile data while, in a reception mode, it decodes such coded facsimile data and reproduces them on a paper sheet. More particularly, the present invention relates to a facsimile apparatus which can reproduce sufficiently legible facsimile data despite successive line errors which may occur at a remote transmitter during transmission.
In a prior art facsimile system, a transmitter produces image data by scanning an original document and codes them scan line by scan line into facsimile data. The facsimile data are transmitted with end-of-line or EOL codes interposed between each adjacent facsimile data. A receiver, on the other hand, decodes the received facsimile data and reproduces them on a copy sheet in the order of reception. Such an apparatus involves a problem, however. If errors occur in a plurality of successive lines of facsimile data during transmission due to noise in the transmission line or the like, the corresponding number of scan lines for data reproduction become omitted altogether. Supposing that a character on one character line is covered by eight scan lines inclusive of interline spacings, more than one half of the character is omitted to make the resulting copy illegible.
To overcome the problem discussed above, there has been proposed a system which repeatedly transmits facsimile data on the same line. This is not fully acceptable in view of the resulting increase in the time period necessary for transmission.